The present invention relates in general to radio frequency identification (RFID) devices. More particularly, the invention relates to the use of multi-functional RFID tag assemblies, passive repeater systems and modular antenna systems to track containers and/or products.
RFID systems are well known in the art. Such systems include relatively large packages containing battery powered transmission/receiving circuitry, such as the identification system disclosed in U.S. Pat. No. 4,274,083, to passive systems in which the transponder receives its power from the base station or interrogator, such as the identification system disclosed in U.S. Pat. No. 4,654,658.
A typical RFID system is made up of reusable tags, an antenna system that interrogates the tags via an RF link and a controller. The host (or computer) system interfaces with the controller and directs the interrogation of the tags. The RFID system thus provides effective means of identifying, monitoring, and controlling materials in a closed loop process. In a factory environment, the tags are employed as the transport mechanism between xe2x80x9cislands of automation,xe2x80x9d providing a record of each process which can be acted upon immediately or downloaded later for analysis. In operation, as a tag passes near an RFID antenna unit, an antenna emits RF signals towards the tag and the tag transmits responses to the antenna. The tags can be powered by an internal battery (i.e., an xe2x80x9cactivexe2x80x9d tag) or by inductive coupling receiving induced power from the RF signals emitted from the antenna (i.e., a xe2x80x9cpassivexe2x80x9d tag). Passive tags have zero maintenance and virtually unlimited life. The life span of an active tag is, however, limited by the lifetime of the battery, although some tags offer replaceable batteries. RFID tags also have limited applicability due to limitations on the operating range.
RFID antenna units are typically employed in manufacturing environments and are used to read tagged items as they pass certain points. The antennas are generally operated in the ranges of 2.45 GHz, 900 MHz or 125 KHz. The noted frequencies are employed to achieve a longer antenna field range. It is, however, well known that at 2.45 GHz and 900 MHz the fields produced by the antenna(s) are affected by virtually everything that passes through the field, including metals and moisture. Metal causes extreme reflection of the fields, while moisture causes extreme absorption of the field. Therefore, any metal object or anything containing moisture, such as the human body, will cause extreme disruption of the field and, hence, the communication of the antenna with the tags.
In an effort to eliminate or substantially reduce the extreme reflection cause by metal objects passing through the field, multiple reflective shields have been employed. The shields cause the field to continuously reflect until it eventually contacts a tag. This is, however, a costly and often impractical solution.
At the other extreme (i.e., 125 KHz), better environmental performance is achieved because metal and moisture generally have less affect on the field. There are, however, several significant drawbacks associated with the noted operating frequency. A major drawback is the high cost, since 100 or more turns in the antenna coil are required to achieve the 125 KHz operating range. Alternatively, an operating frequency of 13.56 MHz can be employed. Although the noted frequency achieves good environmental performance, it is often unable to achieve the operating range of the aforementioned frequencies.
It is therefore an object of the present invention to utilize an RFID antenna system that comprises modular antenna segments that can be connected in a variety of configurations for multiple applications.
It is therefore an object of the present invention to utilize an RFID tag assembly and system to track a product or other article during transportation, storage and distribution.
It is another object of the invention to utilize an RFID tag assembly and system to extend the operating range of a conventional RFID tag.
It is yet another object of the invention to utilize an RFID tag assembly and system to reduce the orientation sensitivity of a conventional RFID tag.
It is still a further object of the invention to utilize cartons having integrated RFID tags to track and identify items during transportation, storage and distribution.
In accordance with the above objects and those that will be mentioned and will become apparent below, the invention comprises a method for communicating with an RFID tag comprising the steps of (i) providing a passive loop modular antenna system, the antenna system comprising a plurality of modular antenna segments adapted to transmit at least a first RF signal to the RFID tag and receive at least a second RF signal from the RFID tag, the antenna segments being removeably connectable to form a plurality of antenna system configurations, at least a first of the plurality of antenna system configurations providing an antenna field, the antenna field providing substantially multi-directional RF transmission of the first RF signal and receipt of the second RF signal, (ii) moving the RFID tag through the antenna field, (iii) transmitting the first RF signal from the antenna system while the RFID tag is moved through the antenna field, and (iv) receiving the second RF signal from the RFID tag.
Preferably, the noted method includes the step of providing configuration means having at least design means for designing at least a first one of the plurality of antenna system configurations, design validation means to validate the design of the first antenna system configuration, and means for providing at least one assembly drawing and the control parameters for the first antenna system configuration.
In a further embodiment of the invention, the method for communicating with at least one RFID tag comprises the steps of (i) providing a RFID reader adapted to provide a magnetic flux field, (ii) providing at least one RFID tag that is disposed on at least a first product container, (iii) providing at least one passive repeater member having at least one substantially continuous passive loop that is adapted and positionable with respect to the RFID reader and tag to couple the RFID reader and tag and redirect the magnetic flux field, (iv) providing the magnetic flux field, and (v) moving the first product container through the magnetic flux field.
Preferably, the RFID tag is removeably attached to the first product container and is adapted to be removed from the first product container and re-attached to at least a second product container.
The invention also comprises a method for tracking an article disposed in a product container, comprising the steps of (i) providing at least a first product container having a plurality of container surfaces and containing at least a first article, (ii) providing a RFID tag assembly having at least one RFID tag that is disposed on at least a first surface of the container, the RFID tag assembly including a first substrate having first and second surfaces, and at least a first passive loop disposed on at least the first surface of the substrate, the first passive loop being adapted to receive at least a first RF signal and transmit at least a second RF signal in response to the first RF signal, the substrate and first passive loop being disposed on the first container surface proximate the RFID tag, the first passive loop being coupled to the RFID tag, (iii) providing at least a first RFID antenna system adapted to provide a first antenna field, the first RFID antenna system being adapted to transmit at least the first RF signal to the RFID tag and receive at least the second RF signal from the RFID tag, (iv) moving the first product container through the first antenna field, (v) transmitting the first RF signal from the antenna system while the RFID tag is moved through the antenna field, and (vi) receiving the second RF signal from the RFID tag.
Preferably, the RFID tag assembly includes a second substrate having first and second surfaces, the second substrate first surface being secured to the first surface of the container, the second substrate second surface being removeably secured to the first substrate second surface, wherein the RFID tag can be removed from the first product container and re-attached to at least the first article or a second product container.